The present invention relates to cooling arrangements for shaft furnaces.
Known in the art is a cooling arrangement for blast furnaces (Japanese Patent Publication No. 45-14642, Nat. Cl. 10A521, published in 1970), comprising spaced apart metallic cooling tubes arranged so that with the cooling arrangement in position the tubes are adjacent to the furnace shell, are substantially parallel to its longitudinal generating line and are interconnected with metallic tie plates by welding, while the space between the cooling tubes and the tie plates interconnecting the same tubes is filled with a refractory material. In the prior art cooling arrangement, the cooling tubes extend along the height of the cooling zone of the furnace shaft and are interconnected by tie plates along both the height and the perimeter of the furnace shaft to thereby provide a rigid structure.
This structure is subjected to extreme thermal loads through the height and the perimeter of the furnace shaft. Under these conditions a rigid structure with the tubes interconnected as hereinabove described experiences considerable thermal stresses leading to break-away of the tie plates from the cooling tubes and, consequently, to gas leakage through the cooling arrangement followed by overheating of the furnace shell resulting its warping and wreckage.
Moreover, due to the structural features the prior art cooling arrangement poses problems in its construction since a stringent observance of its design characteristics is required. Construction of the cooling arrangement is further complicated by the fact that this can be carried out in the furnace only during major repairs or in constructing the furnace to thereby extend the repair (construction) period and to make use of a special-purpose equipment at the construction site. Furthermore, it is to be appreciated that the cooling arrangement is assembled in a restricted space.
It is also to be kept in mind that making such long welds produces more stresses throughout the structure.
During a furnace run, the refractory material disintegrates and falls down to uncover the cooling tubes and therefore to increase heat losses, which result in an excessive consumption of fuel.
The uncovered tubes are exposed to an abrasive action of the dusty gases and the charge materials.